diff --git a/src/backoff.rs b/src/backoff.rs
index e16a63f..2a34abc 100644
--- a/src/backoff.rs
+++ b/src/backoff.rs
@@ -2,7 +2,7 @@ use std::fmt::Debug;
 use std::time::Duration;
 
 /// BackoffBuilder is used to build a new backoff.
-pub trait BackoffBuilder: Default + Debug + Send + Sync + Unpin {
+pub trait BackoffBuilder: Clone + Debug + Send + Sync + Unpin {
     /// The associated backoff that returned by this builder.
     type Backoff: Backoff;
 
diff --git a/src/constant.rs b/src/constant.rs
index 7063ffe..1f8b524 100644
--- a/src/constant.rs
+++ b/src/constant.rs
@@ -31,7 +31,7 @@ use crate::backoff::BackoffBuilder;
 ///     Ok(())
 /// }
 /// ```
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub struct ConstantBuilder {
     delay: Duration,
     max_times: Option<usize>,
diff --git a/src/exponential.rs b/src/exponential.rs
index bf949d7..4081c7a 100644
--- a/src/exponential.rs
+++ b/src/exponential.rs
@@ -36,7 +36,7 @@ use crate::backoff::BackoffBuilder;
 ///     Ok(())
 /// }
 /// ```
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub struct ExponentialBuilder {
     jitter: bool,
     factor: f32,